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Anti-Reflection Coating
As with all uncoated glass substrates; part of the light (about 4% on each
surface) is reflected on the ball lens. Appling an AR coating on the surface
by means of vacuum evaporation the reflection of light can be reduced to
less than 0,1%.
The coating is optimized to get best transmission property at
a given wavelength of light and depends also on the substrate’s index of
reflection. This requires specific coatings for each ball lens material.
The AR coatings offered by
SJC
are specified for the telecom typical wavelengths at 830, 1310 and 1550 nm.
Broadband coatings are available for 810-1310 and 1310-1550 nm. The ball
lenses are coated over the entire surface without an uncoated stripe around
the circumference. This technology is available for diameters from 0.7 to 4
mm. Smaller diameters are being developed.
AR coatings are batched processed; therefore a full capacity batch size is
required to fill the coating chamber. |